Volvo Warning Light Mysteries

My father passed away suddenly and I inherited a 1991 Volvo 240. I know nothing about this car’s history beyond what I was able to find via old receipts- looks like he got regular oil changes. He also had the air conditioner modified recently.

It was driven up to Portland from Vegas. Prior to arrival it got new brakes, oil change, general maintenance. Half way up here I am told the brakes started squealing, which they continued to do until:

On the freeway I noticed the car was heating up. We pulled over, levels were fine, it cooled down, went on to drive. It cooled way down on the freeway, and after the heating problem went away the lights started to go dim. It actually died a few times in stopped traffic, and I was able to restart it. It finally died permanently in traffic- jumping it would not help- it wouldn’t hold a charge.

Replaced the battery and everything seemed fine- started right up- this oddly ceased the squeaky brakes–, but then randomly while driving, all of the warning lights would come on, I would lose power steering, and the warning lights would kind of glow off and on a bit (the battery seemed to stay on the longest), and then they would come back on, flick off one by one, and everything would be fine.

The car has been parked since that episode. I started it the other day and all of the warning lights came on and stayed on. I am really afraid to drive it after the dying-in-traffic incident.

Any ideas on what is causing this? Would driving it to the mechanic be a horrible idea? Thanks for any help you can offer!